Recently, image-forming apparatuses have employed a belt-fixation format in order to meet demands such as downsizing, energy-saving, and high printing and copying speed. Thus, a fixation roller employed in an image-forming apparatus has been replaced by a fixing belt having no end (i.e., an endless belt or endless film).
For shortening the rise time and saving energy, there has been proposed an induction-heating-type belt-fixation format in which a magnetic field is applied to a fixing belt formed of a magnetic metal (e.g., nickel) substrate, to thereby generate eddy current for heating the magnetic metal.
In recent years, there is further demand for a fixing belt of high heat generation efficiency, which belt can be heated to a predetermined temperature over a shorter period of time in a more energy-saving manner. In order to meet the demand, there has been proposed a fixing belt for effectively generating heat via electromagnetic induction and ensuring more flexible choice of layer configuration and layer thickness, which belt has a base layer formed of magnetic metal and having high resistivity and relative permeability; a heating layer formed of a non-magnetic conductive metal and having a resistivity and a relative permeability which are sufficiently lower than those of the base layer; and a surface release layer (see Patent Document 1).
However, the above-proposed fixing belt has a problem in that interlayer delamination between the heating layer and the surface release layer occurs. As a result, heating of the metal layer through electromagnetic induction fails to be attained in some cases, which is problematic. In order to solve the problem, there has been proposed a method for producing an endless belt including heating a surface release layer in a non-oxidizing gas atmosphere (see Patent Document 2). In this production method, undesired oxidation of the heating layer is prevented, whereby adhesion between the heating layer and a layer disposed on the peripheral surface of the heating layer can be enhanced, and the thus-produced endless belt can be heated to a temperature allowing image fixation.